1. Field of the Invention
The invention relates to a channel status determination method and related wireless local area network system and direct link setup method, and more particularly, to a channel status determination method providing a basis for determining a channel status between stations via the stations forwarding beacons of access points (APs), and wireless local area network system and direct link setup method using the same.
2. Description of the Prior Art
In the modern information society, a wireless communication system has become one of the most important ways for exchanging sounds, text messages, data, and video files, etc. In order to improve the quality of communication, the prior art has disclosed various wireless communication technologies for enhancing the spectrum efficiency and transmitting rate of the wireless communication system.
For example, in a wireless communication system conforming to WLAN (wireless local area network) standard IEEE 802.11, a station does not transmit data directly to another station but through access points (APs). Such transmission procedure decreases data throughput; thus, IEEE 802.11e defines a direct link setup (DLS) function allowing data transmission between stations, so as to increase data throughput. Operations thereof are briefly described as follows.
Please refer to FIG. 1. FIG. 1 is a schematic diagram of a WLAN system 10. In the WLAN system 10, if a station 102 intends to transmit data directly to a station 104 via DLS, the station 102 first outputs a DLS request message DLS_Request to an access point 100. The DLS_Request comprises information of a transmitting rate and ability of the station 102, and medium access control (MAC) addresses of the stations 102 and 104. When the access point 100 receives the DLS request message DLS_Request from the station 102, if the access point 100 allows DLS and has confirmed existence of the station 104, the access point 100 forwards the DLS request message DLS_Request to the station 104. When the station 104 receives the DLS request message DLS_Request forwarded by the access point 100, the station 104 responds a DLS response message DLS_Response through the access point 100 to the station 102. If the station 102 successfully receives the DLS response message DLS_Response forwarded by the access point 100, the station 102 and the station 104 start to transmit data without forwarding of the access point 100.
As can be seen from the above, to establish DLS between the station 102 and the station 104, a user must acquire (or have an ability to acquire) MAC addresses of the stations 102 and 104, and then keys or inputs the MAC addresses into a DLS software. Such a procedure is inconvenient, especially for those who lack advanced network knowledge.
In addition, in the process of establishing DLS between the station 102 and the station 104, as long as the DLS request message DLS_Request outputted from the station 102 is accurately transmitted to the station 104 and the DLS response message DLS_Response is accurately transmitted to the station 104, the station 102 and the station 104 can successfully establish DLS. In other words, once the connections between the access point 100 and the station 102 and between the access point 100 and the station 104 are operative, even if the connection between the station 102 and the station 104 can never be established, the prior art still determines DLS feasible, and hence results in operation problems thereafter.
Moreover, when the station 102 intends to terminate DLS, the station 102 outputs a DLS tear down message through the access point 100 to the station 104. When the station 104 receives the DLS tear down message, the station 104 stops the corresponding connection. However, besides the above situation, the prior art does not disclose when should the station 102 output the DLS tear down message. For example, after DLS is established, if the station 102 and the station 104 do not receive data because the connection between the station 102 and the station 104 is interrupted (or never established), or either the station 102 or the station 104 is out of a service area of the access point 100, the station 102 does not output the DLS tear down message.
Thus, the prior art DLS function needs to be improved.